refactor(sleep): decouple engine to top-level skillopt_sleep/ (zero research dep)

Open-source-tool / research-code separation:
  - git mv skillopt/sleep/ -> skillopt_sleep/ (top-level, sibling to the research
    skillopt/ package). History preserved as renames.
  - All imports skillopt.sleep.* -> skillopt_sleep.*.
  - Vendor the validation gate into skillopt_sleep/gate.py (a self-contained copy
    of skillopt.evaluation.gate). The engine now has ZERO dependency on the
    research package — verified: grep finds no `from skillopt.` in skillopt_sleep/,
    and consolidate's gate resolves to skillopt_sleep.gate.
  - Plugin scripts/commands/skill call `-m skillopt_sleep`.

29 tests pass; `python -m skillopt_sleep` runs standalone.

Co-Authored-By: Claude Opus 4 <noreply@anthropic.com>

skillopt_sleep/__init__.py

@@ -0,0 +1,20 @@
+"""SkillOpt-Sleep — nightly offline self-evolution for a local Claude agent.
+
+A Claude Code plugin engine that gives a user's agent a "sleep cycle":
+harvest the day's real session transcripts, mine recurring tasks, replay
+them offline, and consolidate short-term experience into long-term memory
+(CLAUDE.md) and skills (SKILL.md) behind a SkillOpt validation gate.
+
+Synthesizes three ideas:
+  * SkillOpt  — validation-gated bounded text optimization (this repo)
+  * Dreams    — offline memory consolidation, input never mutated
+  * Sleep     — short-term experience -> long-term competence, offline
+
+Public entry points:
+  * skillopt_sleep.cli      — `python -m skillopt_sleep ...`
+  * skillopt_sleep.cycle.run_sleep_cycle(...)
+"""
+from __future__ import annotations
+
+__all__ = ["__version__"]
+__version__ = "0.1.0"